My research interests cover all
areas of mathematical, statistical and theoretical genetics.
A main area of interest is evolutionary
population genetics, in particular statistical and mathematical
aspects of the theory. Population genetics aims at elucidating
the evolutionary process in Mendelian terms. Because of the quantitative
nature of gene transmission, this is a highly mathematical subject.
One specific field of interest is phylogenetic tree reconstruction:
here the DNA sequences of various species are given, and from
these it is desired to reconstruct a tree of evolution. Another
field of interest is the statistical theory arising from the recognition
of the stochastic, or random, aspect of gene replacement processes.
This requires the use of Markov chain theory and also diffusion
theory. A further area of interest in evolutionary genetics is
in the complex multilocus theory arising when arbitrary epistatic
interactions between gene loci are allowed.
A second main interest is the use of
mathematical methods in human genetics, specifically in methods
for mapping disease genes. A recent development made in conjunction
with R. S. Spielman is the transmission/disequilibrium test: this
test is frequently used for fine genetic linkage analysis. Other
interests in this area include the resolution of the ascertainment
sampling problem: this problem arises because of the non-random
sampling frequently used to find the genetic properties of diseases,
and requires the development of new statistical testing and estimation
procedures. I have developed a method which, in a wide variety
of cases, overcomes the problems involved in non-random sampling
and provides a method of analysis whatever the ascertainment process
of the data might be.
A final area of interest is statistical
genomics and computational biology. Especially with the accumulation
of vast quantities
of
data for the human genome project, and of analogous projects
for other species, computer and mathematical methods are needed
for
the storage, retrieval and analysis of DNA sequences. For more
details about ths new area of biology, see web page, http://www.med.upenn.edu/gcb/.
selected
publications
Richard S. Spielman, Laural A. Bastone, Joshua T. Burdick, Warren
J. Ewens, Michael Morely and Vivian G. Cheung. (2007)
Common genetic variants account for differences in gene expression
among
ethnic groups. Nature Genetics 39, 226-231.
Warren J. Ewens and Herbert S. Wilf. (2007) Computing the distribution
of the maximum in balls-in-boxes problems, with applications
to clusters of disease cases. Proc. Nat. Acad.Sci. 104, 11189-11191.
Warren J. Ewens, Arindam Roy Choudhury, Richard Lewontin and
Carsten Wiuf. (2007) Two variance results in population genetics
theory. Math Pop. Studies 14, 93-110.
Cheung, V.G. and W. J. Ewens. (2006) Heterozygous
carriers of Nijmegen breakage syndrome have a distinct gene expression
phenotype.
Genome Research 16, 973-979.
Michael Knapp and Warren J. Ewens. (2005) Direct observation
and unambiguous inference. Biology and Philosophy 20, 925-926.
Anya Plutinski and Warren J. Ewens. (2005) Population genetics.
pp 578-585 in "The Philosophy of Science," S. Sarkar and J. Pfeifer,
eds., Routledge, New York and London.
Ewens, W. J., R Modarres and JL
Gastwirth. (2005) A cautionary note on the use of non-parametric
tests in the analysis of environmental data. Environmetrics 16,
319-326.
Ewens, W. J. and R. S. Spielman. (2005) What
is the significance of a significant TDT? Human Heredity 60,
206-210.
Ewens, W. J. and G. R. Grant, (2004) Statistical
Methods in Bioinformatics. Second Revised Edition. Springer-Verlag,
New York.
Ewens, W. J., (2004) Mathematical Population
Genetics. Second Revised Edition. Springer-Verlag,
New York.
Spielman, R. S. and Ewens, W. J., (2003) Relatives-based Test
for Linkage Disequilibrium: The Transmission/Disequilibrium Test
(TDT). Encyclopedia of the Human Genome, 1007-1010.
Ewens,
W.J., S. Ogino,
D. Leonard, H. Rennert, and R. Wilson. (2002) Genetic risk
assessment in
carrier
testing
for spinal muscular
atrophy Am. J. Med. Genet.110: 301-307.
People